Pouring tube for pressure pouring apparatus



y 1967 E. D. MILLER, JR 3,329,201

POURING TUBE FOR PRESSURE POURING APPARATUS Filed Dec. 11, 1964 l/VVE/VTOR ELDON D.M|LLER, JR.

United States Patent 3,329,201 POURING TUBE FOR PRESSURE POURING APPARATUS Eldon D. Miller, Jr., Bridgeville, Pa., assignor to Harbison-Walker Refractories Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 11, 1964, Ser. No. 417,647 5 Claims. (Cl. 164309) ABSTRACT OF THE DISCLOSURE The present invention is directed to pouring tubes for pressure pouring apparatus. The pouring tubes are composed of erosion-resistant refractory, one end of which is disposed to extend through an aperture in the pressure pouring container and into the material to be poured. The other end is in communication with a mold disposed above the container. The erosion-resistant pouring tube contains a thermally insulating jacket enveloping contiguously the outer surface of the tube extending from the material to be poured to the mold to maintain the temperature of the outer surface as close as possible to the temperature of the material to be poured to thereby prevent a temperature gradient in the tube portion suflicient to cause tensile failure thereof due to tangential stresses.

In the pressure casting of molten metal, the metal is forced from a ladle, upwardly, through a tubular refractory pouring spout, into a mold responsive to pressure differential between a chamber containing the molten metal and the mold. The patent to Zickefoose, No. 3,014,- 155, discloses a certain pressure casting apparatus and is concerned primarily with the pressure pouring tube. The patent sets forth a method for treating the pouring tube by preheating its entirety in sequential steps, to a temperature of about 1800" F., to reduce the possibility of damage to the tube resulting from thermal shock due to sudden excessive temperature changes. The preheating of the tube also serves to minimize the cooling of the metal therein, as is taught by the patent to Sylvester, No. 3,123,877.

In the patent to Strom, No. 2,852,822, a pressure pouring apparatus similar to Zickefoose is shown. The Strom patent discloses applying a nonporous, gas impermeable glazed coating to the outer surface of the tube, to prevent leakage of air through the wall of the tube into the molten steel passing therethrough.

In practice, with contemporary differential pressure pouring apparatus, it has been found that when the pouring tube is immersed in the molten metal bath, a substantial length of tubing existsthe outer surfaces of which are free from contact with the molten metal. The patented apparatus, above mentioned, are not typical of contemporary apparatus, as there hardly is any unexposed tubing surface above the metal line. Incontemporary apparatus having greater unexposed tubing surface, between the metallic head (holding one end of the tubing in the container aperture) and the molten metal surface, problems have recently beenencountered.

When a pouring tube has been immersed in the molten metal contained in a contemporary apparatus and metal flows into the aperture of the tubing, the inner surfaces thereof and the outer surfaces are maintained at approximately the same temperature (i.e. temperature of molten metal) up to the metal line. As the molten metal passes up through the tubing into the mold, the entire inner surface of the tubing is approximately at the same temperature as the outer surfaces immersed in the molten metal. Since the pressure pouring operation proceeds rapidly, the outer surfaces of the tube, which become unexposed 3,329,201 Patented July 4, 1967 to the molten metal as a result of the diminished supply in the chamber, do not cool fast enough to create any difiiculties. However, in these portions of the tubing, where the outer surfaces have never been exposed to the molten metal, the thermal gradient is so great that tangential stresses are incurred to cause tensile failure of the tube. Such failures have been encountered even though the entire tube was preheated to temperatures of about 1800 F., since the heat from the unexposed outer surfaces of the tube was rapidly dissipated, especially with the aid of the metallic head in the aperture of the container, which acted as a heat sink.

Therefore, it is an object of the present invention to provide an improved pouring tube for pressure pouring apparatus.

Another object of the invention is to increase the service life of a pressure pouring tube by reducing tangential stresses along the unexposed outer surfaces thereof.

A further object of the invention is to provide a pressure pouring refractory tube, which in use maintains a substantially uniform thermal gradient between the inner and outer surfaces thereof, to preclude failure resulting from thermal stress.

Other objects of the invention hereinafter.

In order to more fully understand the nature and scope of the invention, reference should be had to the following detailed description and drawing-the single figure of which is an elevation view, partly in cross section, of an apparatus utilizing an embodiment of the present invention.

Briefly, according to an embodiment of the present invention, there is provided an erosion resistant refractory pouring tube suitable for use in pressure pouring apparatus, of the type wherein molten material is forced by pressure differential from a container, through the tube, into a mold disposed exterior the container. The tube contains a relatively thick, thermally insulating jacket enveloping contiguously at least a portion of the outer surface thereof, which in use is free from contact from molten material. The jacket serves to maintain the temperature of the outer surface mentioned, as close as possible to the temperature of the material to be poured, to prevent a temperature gradient in the tube portion and failure due to tangential stresses. It is preferred that the insulating jacket be capable of withstanding temperatures up to about 2350 F.

Referring now to the figure, a pressure pouring apparatus is shown as comprising a downwardly converging, concave cover 10, adapted to be detachably secured to a housing 12 by means of clamps 13. The cover is provided with an air conduit 14, leading to a suitable source of air under pressure, and a release conduit 16 for depressurizing the chamber. The housing is adapted to enclose a ladle 18 containing a refractory lining 20 filled with molten material 22 (i.e. iron, steel, etc.) which is forced upwardly through a pouring tube 24 into the cavity 25 of a mold 26, responsive to an increase in air pressure within the housing. i

The pouring tube 24 of the invention, having a composite portion 27, is secured at its upper end 28 within a bore 30 in a mounting head 32 by means of a suitable refractory mortar 34. The head 32 is arranged on a ring member 36 in a manner well known in the art, which, in turn, is welded to a cover 10 at 38. The head 32 is mounted in such a manner that mold 28, disposed thereon, is inclined slightly from the horizontal. This is to prevent entrapment of air within the mold cavity 26 as the cavity is being filled with molten metal.

The pouring tube 24 may be composed of various refractory materials well known to those skilled in the art.

will become apparent However, it is preferred that the tube be composed of a high alumina refractory material, owing to its resistance to erosion by many metals and slags. Exemplary high alumina refractory materials suitable for use in the pres- "ent invention are disclosed in my United States Patents relatively thick layer or jacket of thermally insulating -material in contiguous contact with the outer surfaces 40,

which surface in use, are free from contact with the molten material. The insulating jacket 40 may be composed of any relatively good, thermally insulating material (which can withstand temperatures of about 1800 F. and, preferably, 2200 F.), since, in many instances, it is desirable to preheat the tubes to these temperatures before exposure to the molten material. As an example, suitable thermal insulating materials are asbestos cement, 50% alumina, 50% silica fibered mats, block insulation, lightweight castable refractories, gunning, and ramming mixes, the various compositions, set forth in Patent 3,125,454, assigned to a common assignee, etc.

The pouring tube may be fabricated in any manner well known to the art. However, casting is preferred.

The composite portion of the tube may be fabricated in a variety of ways, depending upon the particular thermal insulating material employed. For instance, if the material is a castable, ramming, or cementatious type of mix, it may be packed around the outer surfaces of the tube and 'either air dried or heat cured depending upon the properties of the material. The above type mixes could also be comolded with the refractory tube in the casting operation.

If a block type thermal insulation is employed, a sheet thereof may be wrapped around and secured to the outer surfaces of the tube with an adhesive or an equivalent securing system. Further, a refractory insulating mix may be preformed into a cylindrical shape, having an inner diameter closely conforming to the outer diameter of the tube. The cylindrical insulating shape may then be slid .over the tube and retained in position, by a retainer ring joined to the outer surface thereof.

In practice, a gas pressure is exerted at conduit 14 in the chamber 12, which forces a molten metal 22 disposed in cavity 18 downwardly in the cavity and thence up- 'wardly, through the tube 24 at the lower end 29. The metal passes into the cavity 26 of the mold 28 until it is filled. The chamber 12 is then depressurized through release conduit 16. As the metal passes up through the tube, the thermally insulating jacket 40, disposed about the outer surfaces 42 of the tube, serves to maintain a low temperature gradient between the outer and inner surfaces of the tube (maintained at about the temperature of the molten metal), thus preventing tangential stresses which could cause tensile failure at this portion of the tube.

As an example, a pressure pouring tube is fabricated by casting a batch of my high alumina material disclosed in United States Patent 3,067,050. The tube is long, has an inside diameter of 6" and an outside diameter of 10". Similarly, an insulating jacket is fabricated by casting a batch of material disclosed in Patent 3,125,454 (assigned to a common assignee). The jacket is 2 long, has an inside diameter of 10.1" and an outside diameter of 12". The jacket is disposed about the tube and fixed in place at a point just above the height to which the tube will be subjected to contact with molten metal,

Having thus described the invention in detail and with sufiicient particularity as to enable those skilled in the art to practice it, what is desired to have protected by Letters Patent is set forth in the following claims.

I claim:

1. In combination with pressure pouring apparatus of the type wherein liquid material is forced by the exertion of super-atmospheric gas pressure thereagainst from a gas-tight container to a mold disposed exterior the container, means for introducing gas under pressure, a mounting member disposed within an aperture of the container and having a bore extending therethrough into the container, an erosion resistant, refractory pouring tube having one end disposed to extend through the bore in the member and into the material to be poured and having the other end in communication with the mold, and a relatively thick thermally insulating jacket enveloping contiguously a portion of the outer surface of said tube extending from the material to the container aperture a sufficient distance to maintain the temperature of said outer surface as close as possible to the temperature of the material to be poured to thereby prevent a temperature gradient in said tube portion as would cause tensile failure thereof due to tangential stress.

2. A pressure pouring apparatus according to claim 1 in which the pouring tube is composed of a high alumina refractory material.

3. A pressure pouring apparatus according to claim 1 in which the insulating jacket is composed of a refractory material.

4. In pressure pouring apparatus of the type wherein liquid material is forced by a pressure differential from a gas-tight container to a mold disposed exterior the container, the improvement comprising a pouring tube having one end disposed to extend through an aperature in the container and into the material to be poured and having the other end in communication with the mold, and having a relatively thick thermally insulating jacket enveloping contiguously the outer surface thereof extending from the material to the mold to maintain the temperature of said outer surface not extending into the material to be poured as close as possible to the temperature of the material to be poured to thereby prevent a temperature gradient in said tube portion sufiicient to cause tensile failure thereof due to tangential stresses.

5. A refractory pouring tube according to claim 4 in which the thermally insulating jacket is capable of withstanding temperatures up to about 23 50 F.

References Cited UNITED STATES PATENTS 2,371,604 3/ 1945 Brennan 2 2-79 X 2,847,739 8/1958 Sylvester 2269 2,852,822 9/1958 Strom 22-69 FOREIGN PATENTS 526,537 6/ 1956 Canada. 1,157,366 12/1957 France.

620,093 10/1935 Germany.

I. SPENCER OVERHOLSER, Primary Examiner. R. S, ANNEAR, Assistant Examiner. 

1. IN COMBINATION WITH PRESSURE POURING APPARATUS OF THE TYPE WHEREIN LIQUID MATERIAL IS FORCED BY THE EXERTION OF SUPER-ATMOSPHERIC GAS PRESSURE THEREAGAINST FROM A GAS-TIGHT CONTAINER TO A MOLD DISPOSED EXTERIOR THE CONTAINER, MEANS FOR INTRODUCING GAS UNDER PRESSURE, A MOUNTING MEMBER DISPOSED WITHIN AN APERTURE OF THE CONTAINER AND HAVING A BORE EXTENDING THERETHROUGH INTO THE CONTAINER, AN EROSION RESISTANT, REFRACTORY POURING TUBE HAVING ONE END DISPOSED TO EXTEND THROUGH THE BORE IN THE MEMBER AND INTO THE MATERIAL TO BE POURED AND HAVING THE OTHER END IN COMMUNICATION WITH THE MOLD, AND RELATIVELY THICK THERMALLY INSULATING JACKET ENVELOPING CONTIGUOUSLY A PORTION OF THE OUTER SURFACE OF SAID TUBE EXTENDING FROM THE MATERIAL TO THE CONTAINER APERTURE A SUFFICIENT DISTANCE TO MAINTAIN THE TEMPERATURE OF SAID OUTER SURFACE AS CLOSE AS POSSIBLE TO THE TEMPERATURE OF THE MATERIAL TO BE POURED TO THEREBY PREVENT A TEMPERATURE GRADIENT IN SAID TUBE PORTION AS WOULD CAUSE TENSILE FAILURE THEREOF DUE TO TANGENTIAL STRESS. 